1. Field of the Invention
The present invention relates to a circuit board, and a magnetic head incorporating the circuit board. More particularly, the present invention relates to a circuit board capable of protecting an MR magnetic head device, which incorporates the circuit board, against electrostatic breakdown.
2. Description of the Related Art
An example of a conventional magnetic head 201 for use in a computer hard disk is shown in FIG. 17. The magnetic head 201 generally comprises a slider 203, a load beam 202, and a circuit board 204. The slider 203 is attached to a fore end 202a of the load beam 202 through a flexure, and a base plate 209 is attached to an opposite end 202b of the load beam 202. The circuit board 204 is attached to the base plate 209.
The slider 203 includes an MR magnetic head device 208 for reproducing magnetically recorded data, and an inductive head device (not shown) for recording data to be magnetically recorded. From each of these head devices, two lead lines are extended to transmit and receive a reproduced signal and a recording signal to and from the outside of the magnetic head. These four lead lines 205a, 205b, 206a, 206b are connected to the circuit board 204 at the side of the base plate 209 where it is attached to the opposite end 202b of the load beam 202.
The circuit board 204 is formed of a flexible printed board, and includes four leads 215a, 215b, 216a, 216b connected respectively to the lead lines extended from the head devices (i.e., 205a, 205b, 206a, 206b). Mounting terminals 215c, 215d, 216c, 216d are provided respectively midway on the leads 215a, 215b, 216a, 216b. Inspection terminals 215e, 215f, 216e, 216f are provided respectively at ends of the leads 215a, 215b, 216a, 216b. 
The leads 215a, 215b, that are connected to the lead lines 205a, 205b of the MR magnetic head device 208, include lands 223, 224 provided between the mounting terminals 215c, 215d and the inspection terminals 215e, 215f, respectively.
In a conventional magnetic head of this type, the circuit including the MR magnetic head device 208 is typically constructed as a closed circuit by attaching a shunt clip or forming a bonding wire between the lands 223, 224 so as to short the lands 223, 224 together. This is done to prevent electrostatic breakdown of the MR magnetic head device 208 during a period from manufacture of the magnetic head to assembly thereof into a hard disk drive.
This may result in a number of problems. For example, when the lands 223, 224 are shorted together by using a clip, there is a risk that the clip may slip off as result of vibration during transport of the magnetic head. As a result, the MR magnetic head device 208 may suffer electrostatic breakdown.
Also, shorting the lands 223, 224 together by wire bonding requires that a wire-bonding step be included in the manufacturing process of the magnetic head, thereby resulting in an increased production cost of the magnetic head.
In view of the state of the art set forth above, an object of the present invention is to provide a magnetic head capable of positively preventing electrostatic breakdown of an MR magnetic head device, and a method of manufacturing the magnetic head, that overcomes the above-identified problems.
The present invention is directed to a circuit board comprising at least a pair of leads for constructing a circuit, lands connected respectively to the pair of leads, and solder bumps formed respectively on the lands, wherein the solder bumps are arranged in an adjacent relationship. The solder bumps are subsequently crushed, causing peripheral portions of the solder bumps to spread and overlap with each other.
The present invention is also directed to a circuit board comprising at least a pair of leads for constructing a circuit, lands formed for connection respectively to the pair of leads, and a solder bridge for electrically interconnecting the lands, wherein the solder bridge is formed by peripheral portions of the solder bumps formed on the lands so that portions of the solder bumps overlap with each other. Preferably, the solder bridge is formed by crushing the solder bumps formed on the lands to an extent that crushed peripheral portions of the solder bumps are overlapped with each other.
Consequently, the leads constructing the circuit on the circuit board can be easily shorted together by crushing the solder bumps, and the circuit can be formed into a closed circuit.
Moreover, since the solder bridge is formed by the peripheral portions of the solder bumps which are integrally overlapped with each other, the contact area between the solder bumps is increased and the leads can be positively shorted between them.
Further, the present invention is directed to a circuit shorting method for a circuit board comprising at least a pair of leads for constructing a circuit, lands connected respectively to the pair of leads, and solder bumps formed on the lands and positioned adjacent to each other. The method comprises the steps of crushing one of the solder bumps such that a peripheral portion of the one solder bump is pressed to spread outward in a radial direction to approach the other solder bump; and then crushing the other solder bump such that a peripheral portion of the other solder bump is pressed to spread outward in a radial direction to contact with the peripheral portion of the one solder bump, whereby the pair of leads are shorted.
With this circuit shorting method, two solder bumps are contacted with each other by crushing the solder bumps one by one. Therefore, the solder bumps can be each positively crushed to make the leads shorted between them, and the circuit can be positively formed into a closed circuit.
In the above circuit shorting method, the step of crushing the other solder bump is preferably performed until a part of the peripheral portion of the other solder bump overlaps the peripheral portion of the one solder bump.
One feature of this circuit shorting method is that the pair of solder bumps are contacted with each other in an overlapping relation. Thus, the solder bumps are unlikely to be separated, even when the circuit board is bent or flexed. Further, a contact area between the solder bumps is increased and the pair of leads can be positively shorted between them.
In the above circuit shorting method, the solder bumps are preferably each crushed under heating. Heating of the solder bumps causes them to soften, thereby reducing the load required for crushing the solder bumps, and the solder bumps can be positively crushed without damaging the circuit board itself.
In the above circuit shorting method, the pair of solder bumps may be crushed simultaneously underheating. Crushing the solder bumps simultaneously, while being softened under heating, reduces the load required for crushing the solder bumps, and the pair of solder bumps can be positively contacted with each other even when they are crushed simultaneously. Additionally, damage of the circuit board itself can be avoided.
In the above circuit shorting method, the solder bumps are preferably each crushed under heating and rubbing. By heating and rubbing the solder bumps, each solder bump is caused to spread in the planar direction of the circuit board while being crushed. This causes the solder bumps to be more positively contacted with each other.
The present invention is directed to a magnetic head in which a slider including an MR magnetic head device is attached to a fore end of a load beam, a circuit board is attached to an opposite end of the load beam, and a pair of lead lines extended from the MR magnetic head device are connected to the circuit board. The circuit board comprises at least a pair of leads connected respectively to the lead lines and constructing a circuit including the MR magnetic head device in cooperation with the lead lines, lands connected respectively to the leads, and solder bumps formed respectively on the lands. The solder bumps are arranged in an adjacent relationship and, when the solder bumps are crushed, peripheral portions of the solder bumps are pressed to spread and overlap with each other.
The present invention is also directed to a magnetic head in which a slider including an MR magnetic head device is attached to a fore end of a load beam, a circuit board is attached to an opposite end of the load beam, and a pair of lead lines extended from the MR magnetic head device are connected to the circuit board. The circuit board comprises at least a pair of leads connected respectively to the lead lines and constructing a circuit including the MR magnetic head device in cooperation with the lead lines, lands connected respectively to the leads, and a solder bridge for electrically interconnecting the lands. The solder bridge is formed by peripheral portions of the solder bumps formed respectively on the leads and overlapped with each other. The solder bridge is preferably formed by crushing the solder bumps formed on the lands to an extent that crushed peripheral portions of the solder bumps are overlapped with each other.
With respect to the MR magnetic head device, a circuit is constructed with the lead lines extended from the head device and the pair of leads connected to the lead lines. The circuit can be easily formed into a closed circuit by crushing the solder bumps so that the pair of leads are shorted between them. As a result, the MR magnetic head device can be protected against electrostatic breakdown.
The present invention is directed to a method of manufacturing a magnetic head in which a slider including an MR magnetic head device is attached to a fore end of a load beam and a circuit board is attached to an opposite end of the load beam. The circuit board comprises at least a pair of leads connected to the MR magnetic head device, lands connected respectively to the pair of leads, and solder bumps formed respectively on the lands and positioned adjacent to each other The method comprises the steps of crushing one of the solder bumps such that a peripheral portion of the one solder bump is spread outward in a radial direction to approach the other solder bump; and then crushing the other solder bump such that a peripheral portion of the other solder bump is likewise spread outward in a radial direction to contact with the peripheral portion of the one solder bump, whereby the pair of leads are shorted.
With this method of manufacturing a magnetic head, a circuit is constructed by the MR magnetic head device, the lead lines extended from the head device and the pair of leads connected to the lead lines. The circuit is formed into a closed circuit by crushing the solder bumps so that the pair of leads are shorted between them. Therefore, the MR magnetic head device can be protected against electrostatic breakdown.
In the above method of manufacturing a magnetic head, the step of crushing the other solder bump is preferably performed until a part of the peripheral portion of the other solder bump overlaps the peripheral portion of the one solder bump. Since the pair of solder bumps are contacted with each other in an overlapping relationship, the contact area between the solder bumps is increased and the pair of leads can be more positively shorted together, whereby the circuit including the MR magnetic head device can be formed into a closed circuit.
In the above described method of manufacturing a magnetic head, the solder bumps are each preferably crushed under heating. Heating softens the solder bumps, thereby reducing the load required for crushing the solder bumps, and the solder bumps can be crushed without damaging the circuit board itself.
In the above described method of manufacturing a magnetic head, the pair of solder bumps may be crushed simultaneously under heating. Crushing the solder bumps simultaneously while they are being softened under heating, reduces the load required for crushing the solder bumps, and the pair of solder bumps can be positively contacted with each other even when they are crushed simultaneously. Damage of the circuit board can consequently be avoided.
In the above described method of manufacturing a magnetic head, the solder bumps are each preferably crushed under heating and rubbing. By heating and rubbing the solder bumps as they are each crushed, each solder bump is spread in the planar direction of the circuit board while being crushed, which causes the solder bumps to be more positively contacted with each other.